Electrogasdynamic converter with resistive channel

ABSTRACT

An electrogasdynamic converter operating on a gaseous stream of the type including a flow channel having ionizing electrode means in an upstream portion to produce charges in the stream, and collector electrode means spaced downstream from the ionizing electrode means to neutralize the charges carried in the downstream direction by the flow. The converter is operated to establish in the intermediate section of the flow channel between the ionizing electrode means and the collector electrode a high resistance path at the boundary of the flow path for charges carried in the stream. The high resistance may be formed by a thin liquid or solid film at the flow path boundary, or by spaced conductive elements extending through a dielectric channel to be flush with the flow boundary and exposed to the stream. In the latter event, a thin resistive film may be deposited on the outside of the channel to have successive sections thereof connected between the conductive elements. A third alternative utilizes a flow channel constructed of a highly resistive conducting material.

I United States Patent Edward L. Collier Morris Plains;

Meredith C. Gourdine, West Orange; Harold W. McCrae, Upper Montelair, all of [72] Inventors [21 Appl. No. 673,078

[22] Filed Oct. 5, 1967 [45] Patented Oct. 12, 1971 [73] Assignee Gourdine Systems, Inc.

Livingston, NJ.

[54] ELECTROGASDYNAMIC CONVERTER WITH 24 LIQUID Aerosol Return AEROSOL SOURCE 3,405,291 10/1968 Brandmaier 310/10 I FOREIGN PATENTS 848,687 9/1960 Great Britain 310/10 Primary Examiner-D, X. Sliney Attorney-Brumbaugh, Free, Graves & Donohue ABSTRACT: An electrogasdynamic converter operating on a gaseous stream of the type including a flow channel having ionizing electrode means in an upstream portion to produce charges in the stream, and collector electrode means spaced downstream from the ionizing electrode means to neutralize the charges carried in the downstream direction by the flow. The converter is operated to establish in the intermediate section of the flow channel between the ionizing electrode means and the collector electrode a high resistance path at the boundary of the flow path for charges carried in the stream. The high resistance may be formed by a thin liquid or solid film at the flow path boundary, or by spaced conductive elements extending through a dielectric channel to be flush with the flow boundary and exposed to the stream. In the latter event, a thin resistive film may be deposited on the outside of the channel to have successive sections thereof connected between the conductive elements. A third alternative utilizes a flow channel constructed of a highly resistive conducting material.

PATENTEDnm 12 um:

SHEET 10F 2 Aerosol Return uouno AEROSOL 7 SOURCE u :0 29 lOb 13 C F /6. 2 52b 32c 52d 32a 34(00 dpa lOa

INVIiNTURS EDWARD COLLIER BY MEREDITH C. GQURDINEfi HAROLD CCRAE M4,

iheir ATTORNEYS PATENTEDUBT I2 l97| 3,612,923

' SHEET 2 OF 2 74' 77 LIQUID I GAS AEROSOL O 1 SOURCE 11 i '1 I I 51- 22 I l s V -67 1 I I j +0 I; at Q42 1I 1: 2 f i? r K 75\ l 1% //X\ INVIZNIORS EDWARD coLLIER, MEREDITH c. souRDINEa ISY HAROLD McCRAE their A TTOR/VEYS since such returning. charges are notavailable to do useful ELECTROGASDYNAMIC CONVERTER WITH RESISTIVE CHANNEL BACKGROUND OF INVENTION This invention relates to electrogasdynamic conversion apparatus and, specifically, to electrogasdynmic conversion apparatus having a flow channel for a gaseous stream which, in

. an exchange of its kinetic and thermal energies, moves charge 1 particles against a charge-repelling field in the flow channel.

-,charges in the stream. a v t It is by now well appreciated that electrogasdynamic conwerters are most efficient and provide the most attractive utility when the charge concentration in the working gaseous stream passing through the electrogasdynamic channel can be 'made as high as practicable. To the-end of attaining high-conversion efficiencies, many attempts have been directed to car rying as many charges as possible between the ionizingand collector electrodes of the converter in order to obtain'high power output. In the case of DC electrogasdynamic converters, the useful power output is the product of the voltage and current at an external load connected between the collector and ionizing electrodes. It has seemed logical,utherefore, to preclude the upstream return of the chargesin the channel,

workintheload. v It is realized in thezelectrogasdynamic art that higher charge concentrations in the flow. channel can be achieved through the use of an, injected aerosol of multimolecular size, the individual particles of which may be given an appreciable charge approaching saturation. Such particles, because of their lower mobility 'and greater mass, can effectively transport electrical charges to. the collecting region, against the charge-repellingfield, With higher charge concentrations, however, the space charge -field gradient normal to the direction, of flow also. tends to effect a greater deposition of charges and charged particles at the boundary of the flow path before they reach the collector electrode, and this phenomenon is particularly pronounced with regard to charges and charge carriersof higher mobilityand lower mass. .An electrogasdynamic channel itself is generally constructed from nonconducting materials of high dielectric strength to resist dielectric breakdown at high collector potentials. As the-potential increases at the collector electrode, however, a corresponding strengthening of the charge repelling field results, tending to slow down the charge carriers. This action, in turn, results in the premature deposition of charge and charge carriers at the interior boundary of the flow channel toproduce ever increasing charge concentra tions at the channel wall. Eventually,;such unwanted charge concentrations precipitate breakdown of the working stream (and perhaps pans of the flow channel) long before. the designedoptimum collector voltage is reached. Moreover, even though the converter can be made vto perform under conditions in which periodic electric breakdowns occur,.the output voltage tends to be unstable or erratic. Contraryto mos'texpectations, such dielectric collapses can be avoided and the operation of the converter improved by the deliberate provision of a conductive path for the deposited-charges at the channel wall.

SUMMARY OF THE INVENTION leakage path for the charges reaching the flow pathiboundaryf prior to collection, to deplete undesired chargeconcentrations. The total resistance of the path between the collector and ionizing electrodes is selected to be equal to or-greater r than the 'load resistance with which the converter is to operate so that the major portion of the output power is developed across the load, rather than across the high resistance leakage path. In preferred embodiments of the invention, the high..resistance path is comprised of a highly resistive film adjacent the flow path boundary of ajdielectric flowchanneLandmay be formed by either a liquid s' |d material. Where a liquid film is employed, the invent" encompasses converters using -a conduit receiving the stream 'ahdexcess liquidparticles from the converter outlet. I y 1;

In further embodimeri the inventiomthe resistive path may be provided by ase I of condiictive elements mutually spaced in the direction of flovvfancl extending through the wall of the flow chanr'lel for cftibn toa high resistancedeposit at the exterior'oftheflo c nnel. "l M I For a betteru' derstanding of these and other aspects ofthe invention, togetherlwith the objects and. further advantages thereof, reference may be made to the following detailed description and tothe drawings, in which W G .r a FIG. 1 is a cross-sectional view of an-:ele ctrogasdynamic converter channel in accordance with the invention, including a thin-film resistive path adjacent the .flow path boundary at the channel interior; a i

FIG. 2 is a partial cross-sectional representation of a further embodiment of the converter channel, employing conductive segments exposed to the flow path boundary for "establishing an effective resistive path at the channel interior;

FIG. 3 is a cross-sectional view of another embodiment of the invention, employing an annular exhaust conduit for the converter flow;

FIGQ4 is a cross-sectional view of the downstream end of an electrogasdynamic converter, employing an annular 'exhau'st conduit surrounding an electrical load; Y i I FIG. 5 is a pictorial representation of an electrogasdynamic converter employing ahelical exhaust conduit surrounding the flow channel; and FIGS. 6 and 6A are cross-sectional views of an electrogasdynamic converter employing a plurality of small exhaust tubes.

FIG. 1 illustrates a basic converter employing the thin resistivefilm at the channel interior in accordance with the invention. The-converter structure shownis similar to that described and explained in the copending application Ser. No. 436,892, 892, filed Mar. 3, 1965 and assigned to the assignee of the present invention, but the concepts tribe discussed are applicable to other electrogasdynamic channel configurations, as well. The'converter iscomprised of an upstream dielectric section .l0a, an intermediate dielectric section 10b and a downstream collecting section 10c. For convenience of assembly and disassembly, the sections l0a,"l0b and are threaded, as shown at 11, and adjoining sections provided with suitable common O-ring seals Ila, fitting within complementary annular grooves.

ally extending convergenvdivergent flow 'path converg ent in the downstream direction to form a nozzle. At the throat 13 of the nozzle is disposed an annular attracton'electrode 15 slightly downstream of the tip of a corona electrode 16, which is also-a nozzle plug, supported in the streamfrom a spider ar. rangement of radially "extending arms 16a. Connected between the electrodes 14, 16 is a corona current source, represented by the battery 17, for establishing an ionizing field in the flow path near the nozzle throat 13. t

From the throat 13 of the noule, the flow path 12 progressively expands in cross section until it reaches a collector electrode 18 supported in the channel froma similar spider a;- rangement 18a. Together, the corona plug 1 6 and divergent and convergent portions of the flow path I2 form a Laval nozzle for the working gas entering (as shown by the arrow 19) the upstream dielectric extension 20 threaded onto the dielectric section 10a.

As noted above, it is well known that the particulate matter dispersed in an electrogasdynamic stream may be charged to enhance the ion (charge) concentration in the flow path and thus increase the efficiency of conversion. In FIG. 1, an aerosol liquid, e.g., alcohol having relatively low conductance (high resistance), is fed from a source 22 into a supply line 24 connected to the upstream section 20. This section is fon-ned with an annular manifold 26 receiving the liquid from a small internal feed passage 27 communicating with the line 24. The manifold 26, in turn, communicates with the interior of the channel just upstream of the corona electrode 16 through a series of small apertures 28, which spray the liquid into the stream as a fine dispersed liquid mist or aerosol. As the aerosol particles 29 are carried by the stream into the ionizing field region between the electrode 16 and attractor electrode 14, they become ionized or charged, and continue their motion in the channel .toward the collector electrode 18. Because of the transverse space charge field gradient in the channel between the attractor 14 and collector 18, however, a certain proportion of the liquid particles are precipitated at the interior wall of the channel. During operation, the flow of the aerosol liquid from the source 22 is adjusted and maintained at a rate sufficient to produce a number of aerosol particles in the flow path so that their precipitation or condensation forms a thin resistive film 30 coating the interior wall 12 between at least the attractor l4 and collector 18.

The ions and charged particles which are not precipitated at the interior of the channel are collected by the collector electrode 18, which is formed to neutralize the charges in the stream by an action which may be equated to an emission of ions of the opposite polarity. The flow of neutralization current through the collector electrode 18 establishes current flow i through an external load R, connected between the corona and collector electrode 16, 18. The current flow 1),, in turn, develops a potential across the load equal to the potential at the collector electrode. That same potential is also effective to maintain a charge-repelling axial field within the flow path 12. The potential energy of the charged particles in the stream is raised in being moved against that field, with the kinetic energy of the stream being exchanged for electrical energy developed across the load R,

Passing the collector electrode 18, the working gas and excess aerosol particles continue their journey downstream and through thechannel outlet 31 into a flexible dielectric tube 31a at the end of the section 100. The purpose of this tube will be explained shortly in detail.

From the foregoing, it is apparent that the thin resistive film 30 established adjacent the interior wall 12 of the flow channel provides an internal current path along the flow path boundary and extending between the collector electrode 18 and attractor electrode 14. The resistance of the film 30 may be represented by an internal load resistance R,. Charges driven to the flow path boundary under the influence of the space charge are conducted through at least a portion of the resistance R, consequently preventing the buildup of localized high potentials and electrical stresses within the channel. As a result, the potential at the collector electrode may be increased substantially, as by increasing the rate of flow of the working fluid and the ion concentration within the channel, without causing dielectric breakdown of the working gas or channel.

As an alternative to using a highly resistive liquid aerosol to fonn the resistance film 30, the film may comprise a solid material deposit adjacent the flow path boundary on the channel wall 12 to achieve the same result. In general, any suitable material may be used for this purpose, provided only that its conductance renders the film resistance equal to or greater than the load resistance for best efiiciency. Peak output power is realized when R, =R, however, higher output voltages can be attained when R, R,

A further alternative is the construction of the intermediate section 10b from any high resistance material, which may be a conducting ceramic. In this instance, the material will possess a lower conductance than the material used for the thin film,

because of the larger conductive cross section presented to the leakage current charges. Yet another alternative is shown in FIG. 2.

In the device shown in FIG. 2, the single intermediate section 10b in FIG. 1 is replaced with a series of dielectric sections 32a -32e which are threaded as indicated at 34 for convenient construction. Between the upstream nozzle section and section 32a, and between mating adjacent sections 32b -e and 100 is a thin annular metal ring 36 surrounding the flow channel and providing circular surfaces 36a which are substantially flush with the interior wall 12 and exposed to the gaseous stream. Those annular rings 35 are electrically connected through leads 38 to a high resistance network 40 connected between the collector electrode 18 and attractor electrode 14. The leads 38 terminate at separate points in the resistance network 40 which are at different potentials and are separated by individual resistances 40a. The network 40 thus establishes several conductive surfaces in the flow path which are at different potentials, and may actually comprise a conductive ceramic deposit at the outside surfaces of the sections 32a-e. I

It will be understood, of course, that the number of annular rings 36 provided will depend upon the length and design of the particular flow channel, and the invention is not limited to any particular number of conductive elements 36 or any particular spacing between them. It should be remarked, however, that the number and spacing of the conductive elements 36 should provide an effective internal resistance network adequate to establish a leakage current (i, of a magnitude sufficient to prevent electrical breakdown in the flow path. In addition, the spacing and resistance R, should be chosen to preclude secondary electrical discharges between adjacent ones of the conductive elements.

It is noted that the network 40 establishes a high resistance (R,) equivalent to the internal high resistance path between the collector 18 and attractor 14 resulting from the liquid film in the apparatus of FIG. 1. As already' remarked, the resistance R, will equal or exceed the load resistance R, to be powered, so that most of the current (dg/d! in the stream is neutralized at the collector electrode 18 for passage through the load R,

FIGS. 3-6A show various forms and modifications of the basic electrogasdynamic converter of FIG. 1, and are intended for use with a liquid aerosol source for the formation of the high resistance liquid film. In operating an electrogasdynamic' converter on a gaseous stream seeded with aerosol particles, it is usually desirable to return the particles to the liquid aerosol source for reinjection into the system. It is, in part, for this reason that the tube 31a is provided at the outlet of the converter in FIG. 1.

In practice, the tube 31a is led back to the liquid aerosol source 22, as shown, to condense the aerosol and resupply the source. However, when recycling the aerosol, dielectric breakdown in the exhaust return may be experienced unless the concentration of charged particles in the exhaust system is prevented by proper design of the apparatus. Moreover, the aerosol used to form the film in the electrogasdynamic channel may also form the thin resistive film in the exhaust return line to impose a third resistance on the system in parallel with the load R In general, therefore, the total impedance of the exhaust return line should greatly exceed the impedance of the load R, so that the voltage generated in the converter is governed primarily by the electrogasdynarnic parameters of the converter, rather than by the electrical and physical characteristics of the return line. If the foregoing conditions are observed, any resistive film formed at the interior of the exhaust return line benefits the system by providing a leakage path in that line for the drainage of excess charges, thus preventing dielectric breakdown in that part of the system. The apparatus of FIGS. 3-6A are constructed with the foregoing considerations in mind.

Turning now to FIG. 3, the dielectric channel 10 is supported at its upstream end by an annular end plate 44. The end plate 44 is secured, by bolts 45, for example, to the radially extending flange 46 of a generally cylindrical chamber 47 closed at the downstream end of the channel by the member 47a, and at the upstream end by the plate 44. The member 47a is similarly flanged for mounting to the mating flange 46a of the chamber 47, and is formed with a smooth annular recess 48 which serves to decrease the dynamic resistance to the flow and provide a relatively smooth directional transition for the gas stream. The dielectric channel is therefore surrounded by the walls of the chamber 47 to form an annular return flow path or channel 49 receiving the flow from the electrogasdynamic flow path defined by the wall 12. Exiting from the outlet3l of the channel 10, the flow direction is reversed by the member 470 and the stream thereafter continues inside the annular channel 49 in a direction counter to the flow in the channel 10. In the wall of the chamber 47 near the end plate 44 are provided one or more outlets 50 which may be connected to the exhaust return line of the liquid aerosol source. The FIG. 3 unit can be constructed with a diameter approximately twice the transverse dimension of the channel itself and with no appreciable length increase.

In FIG. 4, the annular exhaust flow channel is provided by a similar cylindrical chamber 52 which, in this case, extends from the downstream end of the dielectric channel 10. Supported on an end plate 54 secured to the cylindrical chamber 52 is an interior cylindrical section 56 which, together with the outer chamber 52, forms the annular exhaust channel 58, and provides a cavity 56a. At the upstream end of the inner cylinder 56 is a plate 59 supporting the collector electrode 18. In the cavity 56a of the inner chamber 56 and attached to the plate 59 is an electrical terminal 50 for connection to a load, such as the X-ray tube 62 extending from the terminal 60 through an aperture 63 in the end plate 54. Suitable connections for a current return path to the ionizing electrode circuit may also be provided, as by an electrical connection 64 from the end plate 54 electrically coupled to the corona electrode (not shown). In the FIG. 4 device, the flow exiting from the outlet 31 of the channel guide 10 flows past the collector,

through the annular channel 58 formed between the chambers 52 and S6 and out through the apertures 65, for return to the aerosol injection system.

FIG. 5 shows schematically an arrangement which is useful when extremely high voltages are desired. There, the dielectric channel 10 is immersed in a container 67 holding an insulating oil bath. The tubular return exhaust flow line 31a (see also FIG. I) in this instance is spiralled helically around the channel 10 to return the stream from the downstream end of the channel 10 to the upstream end at the container closure plate 68. From there, the aerosol particles may be condensed in the aerosol source 22 and returned to the channel 10, as indicated schematically by the system flow arrows.

In general, where exhaust tubing is used as the return line for the aerosol, the total length L of the tubing should equal or exceed V/20, where V is the desired output voltage in kilovolts and L is measured in feet units. In a typical installation of the type in FIG. 5, it has been found that the output voltage may be increased from about 100 kv. to 150 kv. by employing the spiral configuration of the exhaust tube 31a, rather than a straight single tube flow path downstream of the collector electrode.

In FIGS. 6 and 6A, the flow channel 10 is supported in a special dielectric chamber 70, in a manner similar to the arrangement in FIG. 3. In FIG. 6, however, the chamber 70 forms a series of elongate secondary exhaust channels 72 disposed circumferentially around the channel 10 and communicating at either end with a plenum 74 and 75. The up stream plenum 75 communicating with the outlet 31 of the electrogasdynamic channel serves to distribute the output flow among the exhaust flow channels 72, while the downstream plenum 74 received the flow from each of those channels and directs the flow to an outlet port 77. From there, the aerosol vapor is returned to the liquid source (not shown).

I 1,, (AIL) In (H- L/ (l) where A us /N ek (2) IL: 18L L l) ac ac RI I. ILRL mn= ac av where 1,, short circuit current 1,, current injected into ion source L length of channel 1, -load current R load resistance R, film resistance V open-circuit voltage P power s permittivity of a free space u has velocity N charge concentration in ion source e electronic charge k particle mobility In general, the geometry of the external exhaust housing or chamber is selected to provide maximum air velocity in the annular space (FIGS. 3 and 4) with a minimum air flow resistance, while allowing a liquid film formation on the inside surfaces of the exhaust region. As previously mentioned, the formation of a liquid film at the interior wall of the exhaust channel facilitates the depletion of excess charges. In this connection, converters of the configuration shown in FIG. 3 were found to give superior performance at 60-90 kv., with the reverse-flow annular exhaust channel establishing a leakage current of approximately 3-5 microamperes. When operating any of the described converters on a highly resistive liquid aerosol substance, the rate of flow of the aerosol in the stream is gradually increased until the short circuit current I becomes stable and the localized channel breakdowns (or areovers) cease. It is under those conditions that the resistive film at the channel interior is established. Moreover, once the short circuit current has stabilized, the liquid aerosol flow through the channel can be increased markedly -for example, up to I00 percentwithout serious fluctuations in performance. 7

Alcohol has been listed as a suitable aerosol material for the practice of the present invention, and in that category may be included ethanol and methanol, and mixtures of those alcohols with water. Also suitable are Freon 22, carbontetrachloride, acetone, etc. The section of the material for the film resistance may be made with optimization of power output in mind, realizing that the physical properties of the vapor formed by the aerosol liquid are important. First, its viscosity must be compatible with the formation and maintenance of the liquid film under the flow rates and flow velocities upon which the converter is to operate. Second, its conductance should be low enough so that the film resistance is equal to or higher than the load resistance. Preferably, the film material has a dielectric strength exceeding 3X10 volts per meter, and has a conductance in the range between about 10" ohms/meter and 10 ohms/meter.

Although the invention has been described with reference to specific embodiments thereof, many modifications and variations may be made by one skilled in the art without departing from the inventive concepts disclosed. Accordingly, all such modifications and variations are intended to be included within the spirit and scope of the appended claims.

1. In a method for effecting a conversion of the energy of a gaseous stream into electrical energy, including ionizing the stream in an upstream portion of a bounded flow path to provide charges therein, neutralizing the charges at a downstream portion of the flow path and establishing an axial chargerepelling field in the flow path over an intermediate portion between the upstream and downstream portions, thereby to generate high electrical potentials, the step of:

establishing adjacent the flow path boundary in the intermediate portion, and over substantially the full axial extent of the intermediate portion, a high resistance path operative to conduct charges electrically contacting the flow path boundary to the upstream portion so as to allow the buildup of high charge potentials within the intermediate portion while preventing dielectric breakdown of the gaseous stream or flow path boundary; and forming in the stream a quantity of liquid particles of suitable viscosity to become charge in the stream and produce a thin liquid film at the flow path boundary.

2. A method as defined in claim 1, further comprising the step of providing a secondary flow boundary downstream of the neutralization of charges to carry the stream containing excess liquid particles.

3. A method according to claim 2, in which the secondary flow boundary has a length exceeding the length of said intermediate section to render the resistance of any liquid film formed therein substantially greater than the film resistance in the intermediate section.

4. A method according to claim I, in which the liquid particles are formed by injecting into the stream the vapor of a condensable liquid.

5. A method according to claim 4, in which the condensable liquid is alcohol.

6. A method according to claim 4, in which the film is formed by mixing with the gaseous flow a proportion of the vaporous substance sufficient to stabilize .the rate at which charges are conducted by the resistive film and to eliminate dielectric breakdown within the gaseous stream.

7. A method according to claim 1, in which the thin liquid film is formed over substantially the entire peripheral extend of the flow path boundary.

8. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for establishing at the flow path boundary of the channel a high resistance path for the conduction away of at least some of the charges carried by the gaseous stream and driven to such boundary, the high resistance path extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means, thereby to allow the buildup of high charge potentials in the intermediate section while simultaneously enabling a controlled rate of discharge for electrical charges at the boundary of the gaseous stream and preventing dielectric breakdown of the gaseous stream or the flow path boundary, said high resistance path having a thin film of conducting resistance liquid material providing a flow path boundary in said intermediate section.

9. Apparatus as defined in claim 8 further comprising:

means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form said resistive film.

10. In combination with apparatus according to claim 9, a source of the liquid substance, said substance having a dielectric strength exceeding 3 10 volts per meter.

11. The combination of claim 10, in which said substance has a conductance in the range between and including about 10" ohms per meter and 10" ohms per meter.

12. The combination of claim 10, in which said substance is selected from the group consisting of alcohol, carbon tetrachloride, acetone, Freon 22 and a mixture with water of any of the preceding substances.

13. Apparatus according to claim 9, further comprising:

conduit means downstream of said collector electrode to carry the stream and excess liquid particles from the channel.

14. Apparatus according to claim 13, in which the conduit means has a length exceeding the axial distance of the flow channel between the collector and ionizing electrode means.

15. Apparatus as defined in claim 14, in which the conduit means has a length, in feet, at least equal to one-twentieth of the potential, in kilovolts, at the collector.

16. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and conduit means downstream of said collector electrode and surrounding the flow channel to define therewith an annular flow path to direct the stream in a direction counter to the direction of flow in the flow channel and operative to carry the stream and excess liquid particles therefrom.

17. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and ionizing electrode means; and

conduit means downstream of said collector electrode providing a series of mutually spaced secondary flow tubes disposed about the outside of and extending in a direction generally parallel to the axis of flow channel to carry the stream and excess liquid particles therefrom.

18. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish in electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and

annular conduit means positioned coaxially downstream of the collector electrode and flow channel to carry the stream and excess liquid particles therefrom.

19. Apparatus as defined in claim 18, in which:

the annular conduit means has a cavity at the center thereof for receiving an electrical load device,

the apparatus further comprising conductor means extending internally of the apparatus between the collector electrode and the cavity interior to provide a terminal connection to the load device.

20. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and

conduit means downstream of said collector electrode having a length exceeding the axial distance of the flow channel between the collector and ionizing electrode means and helically surrounding the flow channel to carry the stream and excess liquid particles therefrom.

21. [n apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential:

means for establishing at the flow path boundary of the channel a high resistance path for the conduction away of at least some of the charges carried by the gaseous stream and driven to such boundary, the high resistance path extending over an intennediate section of the channel between the collector electrode and the ionizing electrode means, thereby to allow the buildup of high charge potentials in the intermediate section while simultaneously enabling a controlled rate of discharge for electrical charges at the boundary of the gaseous stream and preventing dielectric breakdown of the gaseous stream or the flow path boundary, said flow channel is constructed from a dielectric material and the resistive path means includes a series of conductive elements mutually spaced in the direction of How by a dielectric portion of the flow channel and having a portion electrically exposed to the stream and flush with the interior of the flow channel, the elements extending through the flow channel to provide respective terminals at the outside thereof, and a conductive high impedance element having a continuous, thin resistive film on the outside of the flow channel connected between each of successive ones of the terminals. 

1. In a method for effecting a conversion of the energy of a gaseous stream into electrical energy, including ionizing the stream in an upstream portion of a bounded flow path to provide charges therein, neutralizing the charges at a downstream portion of the flow path and establishing an axial charge-repelling field in the flow path over an intermediate portion between the upstream and downstream portions, thereby to generate high electrical potentials, the step of: establishing adjacent the flow path boundary in the intermediate portion, and over substantially the full axial extent of the intermediate portion, a high resistance path operative to conduct charges electrically contacting the flow path boundary to the upstream portion so as to allow the buildup of high charge potentials within the intermediate portion while preventing dielectric breakdown of the gaseous stream or flow path boundary; and forming in the stream a quantity of liquid pArticles of suitable viscosity to become charge in the stream and produce a thin liquid film at the flow path boundary.
 2. A method as defined in claim 1, further comprising the step of providing a secondary flow boundary downstream of the neutralization of charges to carry the stream containing excess liquid particles.
 3. A method according to claim 2, in which the secondary flow boundary has a length exceeding the length of said intermediate section to render the resistance of any liquid film formed therein substantially greater than the film resistance in the intermediate section.
 4. A method according to claim 1, in which the liquid particles are formed by injecting into the stream the vapor of a condensable liquid.
 5. A method according to claim 4, in which the condensable liquid is alcohol.
 6. A method according to claim 4, in which the film is formed by mixing with the gaseous flow a proportion of the vaporous substance sufficient to stabilize the rate at which charges are conducted by the resistive film and to eliminate dielectric breakdown within the gaseous stream.
 7. A method according to claim 1, in which the thin liquid film is formed over substantially the entire peripheral extend of the flow path boundary.
 8. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential: means for establishing at the flow path boundary of the channel a high resistance path for the conduction away of at least some of the charges carried by the gaseous stream and driven to such boundary, the high resistance path extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means, thereby to allow the buildup of high charge potentials in the intermediate section while simultaneously enabling a controlled rate of discharge for electrical charges at the boundary of the gaseous stream and preventing dielectric breakdown of the gaseous stream or the flow path boundary, said high resistance path having a thin film of conducting resistance liquid material providing a flow path boundary in said intermediate section.
 9. Apparatus as defined in claim 8 further comprising: means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form said resistive film.
 10. In combination with apparatus according to claim 9, a source of the liquid substance, said substance having a dielectric strength exceeding 3 X 106 volts per meter.
 11. The combination of claim 10, in which said substance has a conductance in the range between and including about 10 6 ohms per meter and 10 3 ohms per meter.
 12. The combination of claim 10, in which said substance is selected from the group consisting of alcohol, carbon tetrachloride, acetone, Freon 22 and a mixture with water of any of the preceding substances.
 13. Apparatus according to claim 9, further comprising: conduit means downstream of said collector electrode to carry the stream and excess liquid particles from the channel.
 14. Apparatus according to claim 13, in which the conduit means has a length exceeding the axial distance of the flow channel between the collector and ionizing electrode means.
 15. Apparatus as defined in claim 14, in which the conduit means has a length, in feet, at least equal to one-twentieth of the potential, in kilovolts, at the collector.
 16. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential: means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and conduit means downstream of said collector electrode and surrounding the flow channel to define therewith an annular flow path to direct the stream in a direction counter to the direction of flow in the flow channel and operative to carry the stream and excess liquid particles therefrom.
 17. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential: means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and ionizing electrode means; and conduit means downstream of said collector electrode providing a series of mutually spaced secondary flow tubes disposed about the outside of and extending in a direction generally parallel to the axis of flow channel to carry the stream and excess liquid particles therefrom.
 18. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish in electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential: means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and annular conduit means positioned coaxially downstream of the collector electrode and flow channel to carry the stream and excess liquid particles therefrom.
 19. Apparatus as defined in claim 18, in which: the annular conduit means has a cavity at the center thereof for receiving an electrical load device, the apparatus further comprising conductor means extending internally of the apparatus between the collector electrode and the cavity interior to provide a terminal connection to the load device.
 20. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the Flow path region adjacent thereto, thereby to develop an electrical potential: means for dispersing in the stream, at a position upstream of the ionizing electrode means, liquid particles of a substance to be deposited at the flow path boundary to form a high resistance film extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means; and conduit means downstream of said collector electrode having a length exceeding the axial distance of the flow channel between the collector and ionizing electrode means and helically surrounding the flow channel to carry the stream and excess liquid particles therefrom.
 21. In apparatus for converting the energy of a gaseous stream into electrical energy, including a flow channel for the stream, ionizing electrode means in an upstream section of the channel to establish an electrical discharge field productive of mobile charges in the stream and a collector electrode spaced from the ionizing electrode means in the direction of flow of the stream for neutralizing charges carried by the stream in the flow path region adjacent thereto, thereby to develop an electrical potential: means for establishing at the flow path boundary of the channel a high resistance path for the conduction away of at least some of the charges carried by the gaseous stream and driven to such boundary, the high resistance path extending over an intermediate section of the channel between the collector electrode and the ionizing electrode means, thereby to allow the buildup of high charge potentials in the intermediate section while simultaneously enabling a controlled rate of discharge for electrical charges at the boundary of the gaseous stream and preventing dielectric breakdown of the gaseous stream or the flow path boundary, said flow channel is constructed from a dielectric material and the resistive path means includes a series of conductive elements mutually spaced in the direction of flow by a dielectric portion of the flow channel and having a portion electrically exposed to the stream and flush with the interior of the flow channel, the elements extending through the flow channel to provide respective terminals at the outside thereof, and a conductive high impedance element having a continuous, thin resistive film on the outside of the flow channel connected between each of successive ones of the terminals. 